Fe-Cr-Ni alloy for electron gun electrode

ABSTRACT

An electron gun includes a cathode, a control electrode, a screen electrode arranged in front of the control electrode, at least one focusing electrode arranged in front of the screen electrode to form a pre-focusing lens unit, a final accelerating electrode arranged in front of the focusing electrode(s) to form a main lens unit, and a shield cup electrically connected to the final accelerating electrode. The iron-chromium-nickel alloy for the focusing electrode(s), the final accelerating electrode, and the shield cup contains 18-20% or less by weight of chromium, 8-10% by weight of nickel, 0.03% or less by weight of carbon, 1.00% by weight of silicon, 2.00% or less by weight of manganese, 0.04% or less by weight of phosphorous, 0.03% or less by weight of sulfur, a balance of iron, and a trace of impurities, and has an average granularity of 0.010-0.022 mm. The iron-chromium-nickel alloy for the electrode of an electron gun contains a smaller amount of expensive Ni so that the manufacturing cost of electron guns can be greatly reduced. In addition, an electron gun electrode made of the iron-chromium-nickel alloy steel has effective drawing properties and pressing formability. The iron-chromium-nickel alloy is nonmagnetic, and can prevent focusing and convergence drift properties from deteriorating. Accordingly, more reliable cathode ray tubes can be manufactured with the iron-chromium-nickel alloy.

CLAIM OF PRIORITY

[0001] This application makes reference to, incorporates the sameherein, and claims all benefits accruing under 35 U.S.C. §119 from anapplication for Fe—Cr—Ni ALLOY FOR ELECTRON GUN ELECTRODE earlier filedin the Korean Intellectual Property Office on 13 Mar. 2003 and therebyduly assigned Serial No. 2003-15690.

BACKGROUND OF THE INVENTION

[0002] 1. Technical Field

[0003] The present invention relates to an electron gun and, moreparticularly, to an iron-chromium-nickel alloy for electron gunelectrodes that has effective drawing and pressing properties and hasimproved non-magnetic properties so as not to deteriorate focusing andconvergence drift properties.

[0004] 2. Prior Art

[0005] In general, in cathode ray tubes, an electron beam is emittedfrom an electron gun fitted into a neck portion of a bulb whenpredetermined power is applied to the electron gun. The emitted electronbeam is deflected by a deflection yoke on a corn portion of the bulb,and excites the phosphor of a fluorescent layer coated on the innersurface of a display screen panel to form images. Various connectionmethods have been applied to such cathode ray tubes in order to reduceaberration components at the display screen.

[0006] The electron gun includes a triode unit consisting of a cathodeemitting electrons, a control electrode, and a screen electrode. A groupof focusing electrodes is successively arranged in front of the screenelectrode, and a final accelerating electrode forming a main lens unitis installed facing the last focusing electrode.

[0007] The electrodes forming the triode unit of an electron gun aremostly made of a nickel-based super alloy having a small thermalexpansion coefficient. In addition, superior pressing properties arerequired, especially for the control and screen electrodes, which areprocessed to be flat.

[0008] Electrodes other than the control and screen electrodes, inparticular electrodes forming the main lens unit, are formed into a cupshape. Accordingly, materials for these electrodes should be formable bydeep-drawing. Such cup shaped electrodes should remain non-magnetic toprevent deterioration in focusing and convergence drift characteristicsdue to the distortion of deflection magnetic fields. Furthermore, suchelectrodes should have superior resistance to heat and corrosion and lowgas emission so as not to affect the vacuum state of the cathode tube.

[0009] A common material for electrodes is stainless alloy steel. Anavailable stainless alloy steel contains iron (Fe), 15-70% of chromium(Cr), 13.5-15.5% of nickel (Ni), and 0.05% or less of carbon (C) on aweight basis. However, such stainless alloy steel requires a largeamount of expensive Ni, ranging from 13% to 16% by weight, so as to beformable by deep-drawing and to have nonmagnetic properties.

[0010] Therefore, there is a need to develop a new material for electrongun electrodes that contains less Ni for cost reduction and has superiordrawing properties and formability by pressing.

SUMMARY OF THE INVENTION

[0011] The present invention provides an iron-chromium-nickel alloy forelectron gun electrodes, the composition of which is appropriatelyadjusted to provide required drawing and pressing properties and toremain non-magnetic after thermal treatment for improved focusing andconvergence drift properties.

[0012] In accordance with one aspect of the present invention, there isprovided an iron-chromium-nickel alloy for an electrode of an electrongun which includes a cathode, a control electrode, a screen electrodearranged in front of the control electrode, at least one focusingelectrode arranged in front of the screen electrode to form apre-focusing lens unit, a final accelerating electrode arranged in frontof the focusing electrode to form a main lens unit, and a shield cupelectrically connected to the final accelerating electrode. Theiron-chromium-nickel alloy for the focusing electrode(s), the finalaccelerating electrode, and the shield cup comprises 18-20% by weight ofchromium, 8-10% by weight of nickel, 0.03% or less by weight of carbon,1.00% or less by weight of silicon, 2.00% or less by weight ofmanganese, 0.04% or less by weight of phosphorous, 0.03% or less byweight of sulfur, a balance of iron, and a trace of impurities, and hasan average granularity of 0.010-0.022 mm.

[0013] The present invention also provides an iron-chromium-nickel alloyfor an electrode of an electron gun which includes a cathode, a controlelectrode, a screen electrode arranged in front of the controlelectrode, at least one focusing electrode arranged in front of thescreen electrode to form a pre-focusing lens unit, a final acceleratingelectrode arranged in front of the focusing electrode to form a mainlens unit, and a shield cup electrically connected to the finalaccelerating electrode, wherein the iron-chromium-nickel alloy comprises18-20% by weight of chromium, 8-10% by weight of nickel, 0.03% or lessby weight of carbon, 1.00% or less by weight of silicon, 2.00% or lessby weight of manganese, 0.04% or less by weight of phosphorous, 0.03% orless by weight of sulfur, a balance of iron, and a trace of impurities.The iron-chromium-nickel alloy is subjected to annealing at atemperature of 1,000° C. or greater to restore a ferromagneticmartensitic structure formed as a result of cold working into anoriginal non-magnetic ostenitic structure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] A more complete appreciation of the invention, and many of theattendant advantages thereof, will be readily apparent as the samebecomes better understood by reference to the following detaileddescription when considered in conjunction with the accompanyingdrawings in which like reference symbols indicate the same or similarcomponents, wherein:

[0015]FIG. 1 is a vertical sectional view of a general cathode ray tube(CRT);

[0016]FIG. 2 is an exploded perspective view of an electron gun of FIG.1;

[0017]FIG. 3 is a sectional view of a main lens unit of FIG. 2;

[0018]FIG. 4 is a graph of magnetic permeability versus cold workingrate for electrode materials containing different amounts of nickel;

[0019]FIG. 5 is a graph of tensile strength versus average granularityfor electrode materials according to the present invention;

[0020]FIG. 6 is a graph of yield strength versus average granularity forthe electrode materials according to the present invention;

[0021]FIG. 7 is a graph of elongation versus average granularity for theelectrode materials according to the present invention; and

[0022]FIG. 8 is a graph of plastic strain ratio versus averagegranularity for the electrode materials according to the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

[0023] Referring to FIG. 1, a cathode ray tube 10 includes a panel 11with a fluorescent layer (not shown) on its inner surface, a funnel 12fitted to the panel 11 to form a bulb, a shadow mask 13 having numerouselectron beam apertures and spaced a predetermined distance from theinner surface of the panel 11, and a shadow mask frame 14 to which theshadow mask 13 is fixed.

[0024] The position of the shadow mask frame 14 inside the panel 11 isfixed by a stud pin 15 and a hook spring 16 elastically supportedagainst the stud pin 15.

[0025] An electron gun 20, which scans red, green, and blue electronbeams over the fluorescent layer on the inner surface of the panel 11,is fitted into a neck portion 12 a of the funnel 12. A shield cup 17 isinstalled in front of the electron gun 20. A deflection yoke 18 fordeflecting 18 electron beams is installed on a cone portion 12 b of thefunnel 12.

[0026] As shown in FIG. 2, the electron gun 20 includes a plurality ofcathodes 21 as thermion emitters, a control electrode 22 arranged infront of the cathodes 21, a screen electrode 23 arranged in front of thecontrol electrode 22, a group of focusing electrodes 24 thru 27installed in front of the screen electrode 23, and a final acceleratingelectrode 28 installed facing the last focusing electrode 27.

[0027] The three cathodes 21 for emitting red, green, and red thermionsare arranged in a line. The control electrode 22 controls the emissionof electrons from the cathodes 21 using an external signal and hasseparate small electron beam apertures. The screen electrode 23 also hasseparate small electron beam apertures so as to constitute apre-focusing lens unit along with the first focusing electrode 24 facingthe screen electrode 23.

[0028] The focusing electrodes 24 thru 27, which are successivelyarranged in front of the screen electrode 23, constitute an electronlens unit along with the screen electrode 23 so as to focus andaccelerate electron beams.

[0029] The number of focusing electrodes 24 thru 27 is not limited tothe above. The number of focusing electrodes 24 thru 27 may be increasedto form a multi-step focusing electron lens. Each of the focusingelectrodes 24 thru 27 has three in-line electron beam apertures, whichallow electron beams to pass to excite red, green, and blue phosphorscoated on the inner surface of the panel 11. The shape of the electronbeam apertures may be varied depending on the size of the electron lensformed by the electrodes 24 thru 27. Alternatively, a single largeelectron beam aperture may be formed in each of the electrodes 24 thru27.

[0030] In the electron gun 20 with the above structure, a predeterminedvoltage is applied to each of the electrodes 22 thru 28 so as to focusand accelerate electrons emitted from the cathodes 21, which acts as athermion emitter, the electrons passing the electron beam apertures. Theemission of thermions from the cathodes 21 is controlled by a potentialdifference between the cathodes 21 and the control electrode 22. Theelectron beams are accelerated while passing the screen electrode 23,and are focused onto the fluorescent layer by the focusing electrodes 24thru 27 and the final accelerating electrode 28 so as to form images.

[0031] The control electrode 22 and the screen electrode 23 have a flatshape, and the other electrodes 24 thru 28 have a cup shape. Among theseelectrodes, the focusing electrode 27 and the final acceleratingelectrode 28, which form a main lens unit, are formed or drawn into acup shape bypressing, as illustrated in FIG. 3. Electron beam apertures27 a and 28 a are formed therein using a puncher, and burrs 27 b and 28b are formed on the electron beam entry and exit surfaces of thefocusing electrode 27 and the final accelerating electrode 28,respectively.

[0032] According to a feature of the present invention, the electrodes24 thru 28, excluding the control electrode 22 and the screen electrode23, and the shield cup 17 (see FIG. 1), which is installed in front ofthe electron gun 20, contain less nickel compared to conventionalelectron guns and are made of ostenitic iron-chromium-nickel (Fe—Cr—Ni)stainless steel having a particular average granularity and surfaceroughness.

[0033] In particular, an ostenitic Fe—Cr—Ni alloy is used for theelectron gun electrodes in the present invention. The ostenitic Fe—Cr—Nialloy contains 18-20% by weight of Cr, 8-10% by weight of Ni, 0.03% orless by weight of carbon (C), 1.00% or less by weight of silicon (Si),2.00% or less by weight of manganese (Mn), 0.04% or less by weight ofphosphorous (P), 0.03% or less by weight of sulfur (S), a balance of Fe,and a trace of impurities.

[0034] A source alloy having the above composition is processed into amaterial for electron gun electrodes as follows. The source alloy isprocessed through primary cold rolling, annealing, acid washing,secondary skin pass rolling, and degreasing. Then, the resulting sourcealloy is subjected to bright annealing, tension leveling, and slittingfor wrapping.

[0035] The electron gun electrode material has an average granularity of0.01-0.02 mm to provide effective drawing properties, dimensionalaccuracy, and good product appearance.

[0036] The electron gun electrode material according to the presentinvention has a paramagnetic ostenitic structure to ensure non-magneticproperties in order to prevent deterioration in focusing and convergencecharacteristics of the electron gun. Such a microstructure can beachieved with the above ostenitic Fe—Cr—Ni alloy, which contains 18-20%by weight of Cr, 8-10% by weight of Ni, 0.03% or less by weight of C,1.00% or less by weight of Si, 2.00% or less by weight of Mn, 0.04% orless by weight of P, 0.03% or less by weight of S, a balance of Fe, anda trace of impurities.

[0037] When manufacturing an electrode using the above electrodematerial, annealing is performed at a temperature of 1,000° C. orgreater to restore a ferromagnetic martensitic structure formed as aresult of cold working into the original non-magnetic osteniticstructure.

[0038] The electrode material according to the present invention mayhave magnetic properties when the rolling ratio or cold workingpercentage is increased. However, the magnetic properties of theelectrode material disappear after annealing at a temperature of 1,050°C., and the original non-magnetic properties before the cold rolling arerestored.

[0039] The electrode material according to the present inventionoriginally has a non-magnetic ostenitic microstructure. Thisnon-magnetic ostenitic microstructure is changed during cold workinginto a ferromagnetic martensitic microstructure by a modifiedmartensitic transformation mechanism. However, the original non-magneticostenitic microstructure can be recovered through thermal treatment.

[0040] It is preferable that the electrode material contain 8-10% byweight of Ni. If the amount of Ni is less than 8% by weight, theferromagnetic structure cannot be fully changed into the non-magneticstructure after thermal treatment. Using more than 10% by weight of Niis costly and uneconomical.

[0041] The surface roughness of the electrode material affects thecoefficient of friction with a molding puncher and a die and drawingproperties. In addition, the surface roughness is related to the surfacegas emission property and the appearance of the final product. Anappropriate degree of surface roughness is required for desiredappearance of the final product and formability. To this end, thesurface of the electrode material is brush finished so as to have aparticular roughness.

[0042] In the present invention, the surface of the electrode materialis made rough by using an uneven roller, instead of using an abrasive asin general methods, so that the uneven surface pattern of the roller istransferred to the surface of the electrode material. A discontinuousdot pattern, rather than a continuous linear pattern parallel to therolling direction, is preferred as an uneven surface pattern to reducethe anisotropy of the electrode material.

[0043] The electrode material according to the present invention has anarithmetic mean roughness (Ra) of 0.05-0.2 μm and a maximum roughness(Rmax) of 1.5-2.0 μm. The arithmetic mean roughness (Ra) is calculatedin micrometers using the following equation from a roughness curvedefined as y=f(x), wherein the X-axis of the roughness curve denotes thedirection in which an extracted average line having a reference lengthextends, and the Y-axis denotes a direction perpendicular to thedirection in which the extracted average line extends:${Ra} = {\frac{1}{L}{\int_{0}^{L}{{{y(x)}}{x}}}}$

[0044] If the surface roughness of the electrode material exceeds theabove ranges, the lubricating effect is insufficient, and seriousabrasion occurs. As described above, a discontinuous dot pattern ispreferred over a continuous line pattern to reduce the anisotropy of theelectrode material.

[0045] For the dimensional accuracy and hardness of electron gunelectrodes and improved drawing properties, when the focusing electrode27 or the final accelerating electrode 28 has a single large electronbeam aperture and a height of 7 mm or greater, and the shield cup 17 hasa height of 7 mm or greater, it is preferable that the electrodematerial for the focusing electrode 27, the final accelerating electrode28, and the shield cup 17 have a micro Vickers hardness of 165-180 Hv.However, when the focusing electrode 17 or the final acceleratingelectrode 28 has independent small electron beam apertures and a heightof 7 mm or less, an electrode material for the focusing electrode 17 andthe final accelerating electrode 28 should have a micro Vickers hardnessof 160 or 175 Hv. When the focusing electrode 17 or the finalaccelerating electrode 28 includes an inner electrode and has a heightof 7 mm or less, and the shield cup has a height of 7 mm or less, anelectrode material for the focusing electrode 17, the final acceleratingelectrode 28, and the shield chip should have a micro Veckers hardnessof 160 or 175 Hv.

[0046] Hereinafter, the properties of electrode materials according tothe present invention will be described in detail with reference to thefollowing experimental examples.

[0047] Table 1 shows the composition of a conventional electrodematerial (Comparative Example) and the composition ofelectrode materialsaccording to the present invention (Examples 1 thru 6) and their averagegranularity. TABLE 1 Average Example C Si Mn P S Ni Cr Fe granularity,mm Comparative 0.04 0.68 1.61 0.021 0.002 14.12 16.13 Bal. 0.019 ExampleExample 1 0.02 0.62 1.21 0.025 0.003 9.48 18.55 Bal. 0.030 Example 20.02 0.62 1.21 0.025 0.003 9.48 18.55 Bal. 0.025 Example 3 0.02 0.621.21 0.025 0.003 9.48 18.55 Bal. 0.019 Example 4 0.02 0.62 1.21 0.0250.003 9.48 18.55 Bal. 0.013 Example 5 0.02 0.62 1.21 0.025 0.003 9.4818.55 Bal. 0.008 Example 6 0.02 0.62 1.21 0.025 0.003 9.48 18.55 Bal.0.002

[0048] In Table 1 above, the composition of the electrode materials isbased on % by weight. The conventional electrode material was a Fe-16%Cr-14% Ni stainless alloy steel, and the electrode materials of Examples1 thru 6 according to the present invention, were ostenitic stainlessalloy steels, the compositions of which were varied within apredetermined range.

[0049] Referring to Table 1, the electrode materials according to thepresent invention contain only 9.48% by weight of Ni compared to theconventional electrode material, which contains 14.12% by weight of Ni.In addition, the electrode materials according to the present inventioncontain only 0.02% or less by weight of C, compared to the conventionalelectrode material containing 0.04% by weight of C, so as to suppressthe separation of carbon at grain boundaries and improve theanti-corrosion and brittleness of the electrode materials.

[0050] The term average granularity refers to the average size ofostenitic grains split along each grain boundary in the microstructureof stainless alloy steel.

[0051] The properties of the electrode materials with differentcompositions according to the present invention were measured. Theresults are as follows.

[0052]FIG. 4 is a graph of magnetic permeability versus cold workingrate for electrode materials containing different amounts of Ni.

[0053] As shown in FIG. 4, as the cold working rate increases, themagnetic permeability increases more linearly for the electrode materialcontaining 8.0% by weight of Ni (curve C) than for the electrodematerial containing 12% by weight of Ni (curve A) and the electrodematerial containing 9.5% by weight of Ni (curve B).

[0054] In particular, for the electrode material containing 8% by weightof Ni, the magnetic permeability sharply increases with greater coldworking rate. The magnetic permeability indicates how easily magneticfield lines can pass through the electrode material. Ferromagneticmaterials do not allow magnetic field lines to pass through them unlessmagnetic saturation occurs therein. Meanwhile, non-magnetic materialsallow magnetic field lines to easily pass through them. The magneticpermeability is equal to 1 in a vacuum. It is preferable that themagnetic permeability approximate 1 so as not to affect deflectedmagnetic fields and not to deteriorate the focusing properties ofelectron guns.

[0055] FIGS. 5 thru 7 are regression curves of tensile strength, yieldstrength, and elongation versus average granularity for electrodematerials according to the present invention. As shown in FIGS. 5 thru7, the tensile strength and yield strength of the electrode materialdecrease linearly, but the elongation increases, with greater averagegranularity.

[0056] The formability of electrode materials according to the presentinvention was evaluated using a plastic strain ratio, the R-valuesuggested by Lankford, as expressed in the following equation:$R = {\frac{ɛ_{w}}{ɛ_{t}} = {\frac{\ln ( {W_{f}/W_{0}} )}{\ln ( {t_{f}/t_{0}} )} = \frac{\ln ( {W_{f}/W_{0}} )}{\ln ( {W_{0}{l_{0}/W_{f}}l_{f}} )}}}$

[0057] where ε_(w) and ε_(t) denote the strain in the width andthickness directions, respectively, W_(f) and W₀ denote the width of theelectrode material before and after strain, respectively, t_(f) and t₀denote the thickness of the electrode material before and after strain,respectively, W₀l₀ denotes the distance in the width and depthdirections before tensile test, and W_(f)l_(f) denotes the distance inthe width and depth directions after 18% elongation.

[0058] The plastic strain ratio, the R-value, is a factor determiningthe initiation of necking as a result of unstable plastic behavior of anelectrode material during processing, i.e., the local thinning of theelectrode material. A greater R-value means that strain occurs moreeasily in the width and rolling directions due to small resistance tostrain, but necking is more likely to occur in the thickness directiondue to great resistance to strain. Accordingly, the greater the R-value,the better the drawing properties.

[0059] The electrode material according to the present invention has anostenitic structure. The R value of alloy steel having a face centeredcubic structure (FCC), like an ostenitic structure, can be calculatedusing the following multiple regression equation:

R=1.165−6.86×10⁻³(TS/YS)−1.111n+5.928×10⁻³ EL

[0060] where TS denotes tensile strength in Mpa, YS denotes yieldstrength in Mpa, n denotes a strain hardening exponent, and EL denoteselongation percentage.

[0061] In the examples of the present invention, the strain hardeningexponent, n, of the electrode materials is about 0.5. The R-value withrespect average granularity variation was calculated using the abovemultiple regression equation. The results are shown in FIG. 8, and theresults of FIGS. 5 thru 8 are presented in Table 2. TABLE 2 TensileYield Average strength strength Elongation Dimensional Shape ofgranularity, mm (TS), MPa (YS), Mpa (EL), % R-value accuracy burr 0.033593.7 238.0 64.3 0.97 Δ X 0.030 594.9 237.2 62.5 0.96 Δ X 0.028 598.7239.0 60.7 0.95 Δ Δ 0.025 605.2 243.5 59.1 0.94 Δ Δ 0.022 614.4 250.857.5 0.93 ◯ ◯ 0.019 626.2 260.7 56.0 0.93 ◯ ◯ 0.016 640.8 273.3 54.60.92 ◯ ◯ 0.013 658.0 288.6 53.3 0.91 ◯ ◯ 0.010 677.9 306.6 52.1 0.90 ◯ ◯0.008 700.4 327.3 50.9 0.90 Δ ◯ 0.005 725.7 350.7 49.9 0.89 Δ ◯ 0.002753.6 376.8 48.9 0.89 Δ ◯

[0062] Referring to FIG. 8 and Table 2, the plastic strain ratio,R-value, increases with greater average granularity. However, it ispreferable that the average granularity be in a range of 0.010-0.022 mmin terms of dimensional accuracy and the shape of burr after electrodeformation.

[0063] As described above, the Fe—Cr—Ni alloy steel for electron gunelectrodes according to the present invention, the composition of whichis adjusted within a predetermined range for a particular averagegranularity and surface roughness, provides the following effects.

[0064] The Fe—Cr—Ni alloy steel for electron gun electrodes contains asmaller amount of expensive Ni, compared to conventional ones, so thatthe manufacturing cost of electron guns can be greatly reduced. Inaddition, an electron gun electrode made of the Fe—Cr—Ni alloy steel haseffective drawing properties and pressing formability. The Fe—Cr—Nialloy steel is non-magnetic and can prevent focusing and convergencedrift properties from deteriorating. Accordingly, more reliable cathoderay tubes can be manufactured with the Fe—Cr—Ni alloy steel.

[0065] While the present invention has been particularly shown anddescribed with reference to exemplary embodiments thereof, it will beunderstood by those of ordinary skill in the art that various changes inform and detail may be made therein without departing from the spiritand scope of the present invention as defined by the following claims.

What is claimed is:
 1. An iron-chromium-nickel alloy for an electrode ofan electron gun which includes a cathode, a control electrode, a screenelectrode arranged in front of said control electrode, at least onefocusing electrode arranged in front of said screen electrode to form apre-focusing lens unit, a final accelerating electrode arranged in frontof said at least focusing electrode to form a main lens unit, and ashield cup electrically connected to said final accelerating electrode,said iron-chromium-nickel alloy for said at least one focusingelectrode, said final accelerating electrode, and said shield cupcomprising chromium in a range of 18-20% by weight, nickel in a range of8-10% by weight, no greater than 0.03% by weight of carbon, no greaterthan 1.00% by weight of silicon, no greater than 2.00% by weight ofmanganese, no greater than 0.04% by weight of phosphorous, no greaterthan 0.03% by weight of sulfur, a balance of iron, and a trace ofimpurities.
 2. The iron-chromium-nickel alloy of claim 1, having asurface roughness Ra in a range of 0.05-0.2 μm and a maximum roughnessRmax in a range of 1.5-2.0 μm.
 3. The iron-chromium-nickel alloy ofclaim 2, wherein the surface roughness originates from a surface patternof said iron-chromium-nickel alloy formed using an uneven roller.
 4. Theiron-chromium-nickel alloy of claim 3, wherein the surface pattern is adiscontinuous dot pattern parallel to a rolling direction for smalleranisotropy of the iron-chromium-nickel alloy.
 5. Theiron-chromium-nickel alloy of claim 1, wherein one of said at least onefocusing electrode and said final accelerating electrode has a singlelarge electron beam aperture and a height of at least 7 mm.
 6. Theiron-chromium-nickel alloy of claim 5, having a micro Vickers hardnessin a range of 165-180 Hv when used for said at least one focusingelectrode and said final accelerating electrode having a single largeelectron beam aperture.
 7. The iron-chromium-nickel alloy of claim 1,wherein said shield cup has a height of at least 7 mm.
 8. Theiron-chromium-nickel alloy of claim 7, having a micro Vickers hardnessin a range of 165-180 Hv when used for said shield cup.
 9. Theiron-chromium-nickel alloy of claim 1, wherein one of said at least onefocusing electrode and said final accelerating electrode has independentsmall electron beam apertures and a height no greater than 7 mm.
 10. Theiron-chromium-nickel alloy of claim 9, having a micro Vickers hardnessin a range of 160-175 Hv when used for said at least one focusingelectrode and said final accelerating electrode having independent smallelectron beam apertures.
 11. The iron-chromium-nickel alloy of claim 1,wherein one of said at least one focusing electrode and said finalaccelerating electrode includes an inner electrode and has a height nogreater than 7 mm.
 12. The iron-chromium-nickel alloy of claim 11,having a micro Vickers hardness in a range of 160-175 Hv when used forsaid at least one focusing electrode and said final acceleratingelectrode.
 13. The iron-chromium-nickel alloy of claim 1, having anaverage granularity in a range of 0.010-0.022 mm.
 14. Theiron-chromium-nickel alloy of claim 1, wherein said alloy is processedinto a material for said electrode of said electron gun by at least oneof primary cold rolling, annealing, acid washing, secondary skin passrolling and degreasing.
 15. The iron-chromium-nickel alloy of claim 1,wherein said alloy is subject to at least one of bright annealing,tension leveling and slitting for wrapping.
 16. An iron-chromium-nickelalloy for an electrode of an electron gun which includes a cathode, acontrol electrode, a screen electrode arranged in front of said controlelectrode, at least one focusing electrode arranged in front of saidscreen electrode to form a pre-focusing lens unit, a final acceleratingelectrode arranged in front of said at least one focusing electrode toform a main lens unit, and a shield cup electrically connected to saidfinal accelerating electrode, said iron-chromium-nickel alloy for saidat least one focusing electrode, said final accelerating electrode, andsaid shield cup comprising chromium in a range of 18-20% by weight,nickel in a range of 8-10% by weight, no greater than 0.03% by weight ofcarbon, no greater than 1.00% by weight of silicon, no greater than2.00% by weight of manganese, no greater than 0.04% by weight ofphosphorous, no greater than 0.03% by weight of sulfur, a balance ofiron, and a trace of impurities, wherein said iron-chromium-nickel alloyis subjected to annealing at a temperature of no less than 1,000° C. torestore a ferromagnetic martensitic structure formed as a result of coldworking into an original non-magnetic ostenitic structure.
 17. Theiron-chromium-nickel alloy of claim 16, having an average granularity ina range of 0.010-0.022 mm when used for said at least one focusingelectrode, said final accelerating electrode, and said shield cup. 18.The iron-chromium-nickel alloy of claim 16, having a surface roughnessRa in a range of 0.05-0.2 μm and a maximum roughness Rmax in a range of1.5-2.0 μm.
 19. The iron-chromium-nickel alloy of claim 16, wherein saidalloy is processed into a material for said electrode of said electrongun by at least one of primary cold rolling, annealing, acid washing,secondary skin pass rolling and degreasing.
 20. The iron-chromium-nickelalloy of claim 16, wherein said alloy is subject to at least one ofbright annealing, tension leveling and slitting for wrapping.